Working chamber assembly of a rotary piston engine

ABSTRACT

Described here are the working chamber assembly of a rotary engine comprising the outer cover and first and second piston assemblies, each of which assemblies includes a piston hub to which coaxial piston shafts and at least one pair of diametrically opposite pistons are affixed; circular seal means housed along the crevice between the two piston assemblies, and along the crevices between the two piston assemblies and the outer cover; seal means housed along the convex outer ridge surface of each piston; and a lubricant oil delivery/recycling system to those seal means. Piston rings are provided with a centrifugal force containment mechanism to minimize the negative effect of centrifugal force on them.

FIELD OF THE INVENTION

[0001] This invention relates generally to the working chamber assembly of a rotary piston engine that includes first- and second-piston assemblies interconnected for alternate variable-speed rotation whereby pistons of the slower piston assembly comprises trailing pistons during the power and intake phases of the engine operating cycle.

BACKGROUND OF THE INVENTION

[0002] Gas leaks between subchambers are a major problem faced by the only commercially available Wankel rotary piston engine. In the so-called cat-and-mouse type rotary engines, such as those found in U.S. Pat. No. 5,133,317—Sakita; U.S. Pat. No. 4,901,694 Sakita; U.S. Pat. No. 4,028,019—Wildhaber; and U.S. Pat. No. 3,398,643—Schudt, the prevention of gas leaks is critically important in achieving high fuel efficiency. In U.S. patent application Ser. No. 09/898,983 by the present inventor, Sakita describes a cat-and-mouse type rotary engine with embedded sparkplugs within pistons as one of means of preventing gas leaks. Embedding sparkplugs in pistons should contribute to better sealing of engine subchambers, but that alone will not eliminate the gas leak problem. The present invention is a further extension of the rotary engine technology described in the aforementioned patent application by this inventor.

[0003] The cat-and-mouse type rotary piston engine is, in general, more complex in design than the Wankel engine, and the lubricant oil delivery method adopted by the Wankel engine namely, direct injection of oil into the fuel/air mix or mixing oil into gasoline, may not suffice for the engine type of our concern; thus, a new method of lubricating friction-causing parts of the working chamber assembly components is necessary.

OBJECTS OF THE INVENTION

[0004] An object of this invention is the provision of a working chamber assembly that is equipped with seal means that will minimize gas leaks.

[0005] An object of this invention is the provision of a working chamber assembly that is able to operate without causing undesirable gaps between the working chamber walls and the piston rings.

[0006] An object of this invention is the provision of a lubrication oil delivery/recycle system for the friction-causing parts of engine's working chamber assembly.

[0007] An object of this invention is the provision of a mechanism that eliminates or reduces undesirable effects of centrifugal force to seal means including piston rings.

SUMMARY OF THE INVENTION

[0008] A working chamber assembly of a rotary piston engine to which the present invention is applied comprises first- and second-piston assemblies that rotate about a rotational axis, and a stationary outer cover. The working chamber formed by these three parts is toroidal or quasi-toroidal shaped, in which the piston surface is circular, oval or ellipsoidal. Each piston assembly includes one or more pairs of diametrically opposed pistons and a piston hub to which these pistons are attached, and a coaxial piston shaft to which the piston hub is attached. The pair of pistons divides the working chamber into a plurality of subchambers in which a single pair of diametrically opposed pistons per piston assembly provides four subchambers in the working chamber, and two pairs of diametrically opposed pistons per piston assembly provide eight subchambers.

[0009] The present invention includes seal means we call “chamber rings” that are housed along the crevices between the outer cover and the piston hubs, and between the piston hubs. A chamber ring will not be able to completely cover the inner edge of a crevice near the working chamber wall, and it can become a cause of gas leaks between subchambers. In addition, the possible misalignment of neighboring chamber wall sections due to the contraction/expansion of working chamber assembly components and/or imprecise construction of the engine's working chamber may not only enlarge the gap at the mouth of the crevice, but could also create an unmanageable gap between the chamber wall and the piston ring. A way of preventing this from occurring or minimizing its effect must be provided. In this invention, we propose a seal means we call a “bridge seal” for this purpose, and a “journal ring” to minimize vertical misalignment of the piston assemblies. In addition, we pay special consideration to the location of crevices and the shape of pistons to minimize the misalignment of neighboring working chamber wall segments.

[0010] As in a conventional reciprocating engine, in the rotary piston engine described here, each piston ring is housed in a groove, and is not affixed to the body of the piston. Thus, the piston ring can move outward or inward (or upward or downward) within the groove. Centrifugal force working on the piston ring will push the inner part of the piston ring toward the piston body and away from the working chamber wall, and will push the outer part of the piston ring toward the working chamber wall and away from the piston body. Thus the inner part of the piston ring will tend to lose effectiveness in sealing, and the outer part of the piston ring will tend to cause excessively high friction against the outer wall of the working chamber especially when the engine is operated at high rotational speeds. One way to reduce the effects of centrifugal force on the piston rings is to place a strong spring means behind the piston ring between the piston ring and the groove, but this alone will not be adequate for high rpm operation. Thus, there is need for a mechanism that will reduce/eliminate the effects of centrifugal force working on the piston ring. This invention provides such a means.

[0011] In the Wankel rotary engine, lubricant oil is either directly sprayed into the working chamber or added to gasoline. These methods may suffice for piston rings, but may not be adequate for chamber rings which are not exposed to the wall surface of the working chamber of the engine of the present invention. Thus, there is need for a means to deliver and recycle lubrication oil to different parts of the engine. This invention provides such a means.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other objects and advantages of this invention will be better understood from the following description when considered with the accompanying drawings. It should be understood that the drawings are for purposes of illustration only and not by way of limitation of the invention. In the drawings, like reference characters refer to the same parts in the several views:

[0013]FIG. 1 is an exploded isometric view of a working chamber assembly of a rotary piston engine embodying the present invention;

[0014]FIG. 2 is a cross-sectional view of the working chamber including piston rings, chamber rings, bridge seals, and journal rings embodying the present invention;

[0015]FIG. 3 is a skeletal view of the working chamber with emphasis on piston rings and chamber rings taken from A-A of FIG. 2;

[0016]FIG. 4 is a view from the bottom of the working chamber showing the outer cover's wall surface at the exhaust and intake ports;

[0017]FIG. 5 is an enlarged cross-sectional view of a piston with a piston ring, chamber rings, and bridge seals;

[0018]FIG. 6 is a view of a piston with piston rings and bridge seals taken from B-B of FIG. 5;

[0019]FIG. 7 is a cross-sectional view of a piston showing a schematic illustration of a piston ring and centrifugal force containment mechanisms;

[0020]FIG. 8 is a view of a piston with a piston ring and one of the centrifugal force containment mechanisms taken from C-C of FIG. 7;

[0021]FIG. 9 is an enlarged cross-sectional view of the crevice between a piston, a piston hub, and outer cover including a view of a chamber ring, a piston ring, and a bridge seal;

[0022]FIG. 10 is an enlarged cross-sectional view of the crevice between a piston, a piston hub, and outer cover including a view of a chamber ring and a bridge seal of different design;

[0023]FIG. 11 is an enlarged cross-sectional view of the crevice between a piston, a piston hub, and outer cover including a view of a chamber ring and a piston ring of different design;

[0024]FIG. 12 is an enlarged cross-sectional view of the crevice between a piston hub and outer cover including a view of a chamber ring, a piston ring, and a bridge seal;

[0025]FIG. 13 is an enlarged cross-sectional view of the crevice between two piston hubs including a view of a chamber ring, a bridge seal, a piston ring, and a centrifugal force containment mechanism for a bridge seal;

[0026]FIG. 14 is a cross-sectional view of the chamber ring between the two piston hubs;

[0027]FIG. 15 is a cross-sectional view of a piston and chamber rings of alternative design;

[0028]FIG. 16 is a cross-sectional view of a piston showing a schematic illustration of a piston ring and a centrifugal force containment mechanism of an alternative design;

[0029]FIG. 17 is a cross-sectional view of a working chamber assembly including an oil delivery/recycling system;

[0030]FIG. 18 is a cross-sectional view of a piston hub (which is affixed to the inner piston shaft) and a chamber ring with oil bores and grooves in the working surface of the piston hub, wherein the working surface indicates the surface at which two metal surfaces (piston hub and chamber ring in this case) rub against each other;

[0031]FIG. 19 is a cross-sectional view of the inner piston shaft, a piston hub (which is affixed to the outer piston shaft), and a chamber ring with oil bores and grooves in the working surface of the piston hub;

[0032]FIG. 20 is an enlarged view of oil paths between the main oil bore in the inner shaft and the piston ring;

[0033]FIG. 21 is an enlarged cross-sectional view of an oil bore across a bridge seal.

DETAILED DESCRIPTION OF THE INVENTION

[0034] Engine's Working Chamber

[0035] Reference is now made to FIG. 1 of the drawings wherein the engine's working chamber assembly comprising piston assemblies 30, 32, and the stationary outer cover 59 are shown. The working chamber formed by the working chamber assembly is divided into two pairs of diametrically opposed subchambers by the piston assemblies 30 and 32. The piston assemblies 30 and 32 are rotatable about a common axis 40 and, in operation, rotate in the direction indicated by an arrow 42. The piston assembly 30 includes a pair of diametrically opposed pistons 30A and 30B attached to a piston hub 30C, and the piston assembly 32 includes a pair of diametrically opposed pistons 32A and 32B attached to a piston hub 32C. The piston hub 30C is affixed to the outer piston shaft 36, and the piston hub 32C to the inner piston shaft 38, wherein the outer piston shaft 36 is rotatably mounted to the inner tubular shaft 38.

[0036] The pistons affixed to the piston assemblies 30 and 32 are substantially identical in geometric design and construction, each having three surfaces; i.e. two circular- or oval-shaped piston surfaces each of which faces a subchamber, and an outer convex surface that faces the working chamber wall. Piston rings 50 are housed along the outer convex surfaces of the pistons 30A and 30B. Piston rings 52 are housed along the outer convex surfaces of the pistons 32A and 32B. The piston assemblies 30 and 32 are interconnected by a set of gears (not shown in FIG. 1) for alternate variable-speed rotation whereby pistons of the slower piston assembly comprise trailing pistons during the power and intake phases of the engine operating cycle. A spark plug is mounted within each piston, but is not shown in FIG. 1 or in any other figures. The engine's working chamber assembly is also shown in FIGS. 2, 3 and 17 of the drawings.

[0037] Reference is now made to FIG. 2 of the drawings, wherein a cross-sectional view of the engine's working chamber assembly, comprising the outer cover 59 and the piston assemblies 30 and 32, is shown. The chamber wall 33 is formed by piston assemblies 30, 32 and the outer cover 59. The piston assemblies 30 and 32 rotate around the common axis 40 at different speeds while the engine is in operation, and thus the parts of the chamber walls formed by the piston assemblies 30 and 32 rotate as the piston assemblies 30 and 32 rotate, while the part of the chamber wall formed by the outer cover 59 remains stationary.

[0038] The piston hub 32C and the outer cover 59 are separated by a crevice, as are the piston hub 30C and the outer cover 59 and the piston hubs 30C and 32C.

[0039] A journal ring 100, which shares the rotational axis 40 with the piston shafts 36 and 38, is placed between the piston hubs 30C and 32C, wherein a portion of the journal ring 100 is placed in a ring-shaped groove in the piston hub 32C, and the rest of the journal ring 100 is placed in a ring-shaped groove in the piston hub 30. The journal ring 100 has a broken segment and it exerts outward pressure by the spring effect of the ring itself and by a spring (not shown) that is inserted in the broken segment. It allows horizontal movements of the piston assemblies 30 and 32, but it prevents radial movements of the two piston assemblies.

[0040] A chamber ring 47 is housed in a circular groove in the outer cover 59 along the cylindrical crevice between the outer cover 59 and the piston hub 32C. Similarly, a chamber ring 48 is housed in a circular groove in the outer cover 59 along the cylindrical crevice between the outer cover 59 and the piston hub 30C. A chamber ring 46 is housed in circular grooves in the piston hubs 30C and 32C along the crevice between the piston hubs 30C and 32C. The chamber rings 46, 47, and 48 seal off the crevices between the working chamber and outer atmosphere.

[0041] The piston rings 52 are housed in piston ring grooves along the outer convex surfaces of the pistons 32A and 32B, and seal off the crevices between the pistons 32A and 32B and the parts of the chamber wall 33 formed by the piston hub 30C and the outer cover 59. Similarly, the piston rings 50 (not shown in FIG. 2) are housed in piston ring grooves along the outer convex surfaces of the pistons 30A and 30B, and seal off the crevices between the pistons 30A and 30B and the parts of the chamber wall 33 created by the piston hub 32C and the outer cover 59 (see FIG. 3 for piston ring 50). The piston ring grooves are designed in such a manner that a piston ring fits very tightly into the groove, and there is practically no space for air to seep into the piston grooves. The spring effect of the piston rings 52 and mechanically generated force from springs behind the piston rings in the back clearance of the grooves, wherein the back clearance is the space between the ring and the back wall of the groove, may act to push the piston rings against the working chamber wall 33 to keep the air tightness of each subchamber by mechanical pressure alone.

[0042] Bridge seals 61, 62, and 65 are housed in grooves along the outer convex surface of the piston 32A between the piston rings 52. Bridge seals 63, 64, and 66 are housed in grooves along the outer convex surface of the piston 32B between the piston rings 52. The bridge seals 61 and 63 cover the crevices formed by the outer cover 59 and the piston hub 32C. The bridge seals 62 and 64 cover the crevices formed by the outer cover 59 and the piston assembly 30. The bridge seals 65 and 66 cover the crevice formed by the piston hubs 30C and 32C.

[0043] Side wall rings 101 and 102 are affixed to the outer cover 59 facing the crevice between the outer cover 59 and the piston hub 32C, and the crevice between the outer cover 59 and the piston hub 30C, respectively. Journal rings 103 and 104 are affixed to the outer cover facing the gap between the outer cover 59 and the inner shaft 38, and the gap between the outer cover 59 and the outer shaft 36, respectively. Another journal ring 105 is affixed to outer shaft 38 facing the crevice between inner shaft 38 and outer shaft 36 at the outer end of the coaxial shafts. The journal rings 103, 104, and 105 are given inward pressure by a spring means to maintain stable rotation of the piston shafts. The outer cover 59 is equipped with an opening for an exhaust port 54.

[0044] Working Chamber's Seal Means

[0045] Reference is now made to FIGS. 3 and 4 of the drawings, wherein a skeletal view taken from A of FIG. 2 showing chamber rings and piston rings for a four-piston engine is presented. As shown in FIG. 3, the outer cover 59 comprises two one-half pieces 59A and 59B which are attached with bolts and nuts 59C. The chamber rings 46, 47, and 48 (not shown in FIG. 3) are mounted in such a manner that the broken segment(s) will not cause problems in engine operation. As FIG. 3 shows, a broken segment 45 of chamber ring 46 is placed in the segment that is covered by the piston 32A to prevent gas leaks through the broken segment, and a broken segment of the chamber ring 47 is placed in the segment that has the exhaust port 54.

[0046] The piston rings 52 are housed in grooves along the outer convex surface of the pistons 32A and 32B, and similarly, the piston rings 50 are housed in grooves along the outer convex surface of the pistons 30A and 30B. A portion of chamber wall is cut open for the exhaust and intake ports, 54 and 56, respectively, and it is replaced by a grate-like piece of metal 60 shown in FIG. 4 so that piston rings will glide through that section. The pistons 30A, 30B, 32A, 32B are slightly (by a fraction of a millimeter) smaller than the bore of the working chamber, thus crevices between the chamber wall 33 and the pistons 30A, 30B, 32A and 32B are sealed off not by the pistons but by the piston rings 50 and 52.

[0047] Reference is now made to FIGS. 5 and 6 of the drawings. FIG. 5 shows an enlarged cross-sectional view of the piston 32A with piston ring 52, and the chamber rings 46, 47 and 48. The chamber ring 47 is housed in a groove in the outer cover 59 along the inner end of the crevice between the outer cover 59 and the piston hub 32C. The chamber ring groove holds a spring means in the back and outer side clearances, wherein the outer side clearance is the space between the ring and the outer side wall (upper side wall in the figure) of the groove, and it constantly pushes the chamber ring 47 toward working the chamber wall 33 and the piston hub 32C to seal off the gap created by the crevice. Similarly, the chamber ring 48 is housed in a groove in the outer cover 59 along the inner end of the crevice between the outer cover 59 and the piston hub 30C. The groove holds a spring means in the back and side clearances, and it constantly pushes the chamber ring 48 toward the working chamber wall 33 and the piston hub 30C to seal off the gap between piston hub 30C and the outer cover 59. The chamber ring 46 is housed in grooves that face each other in the piston hubs 30C and 32C. The outer wall (upper wall in FIG. 5) of each of those grooves has a conical surface, and the inner wall (lower wall in FIG. 5) has a cylindrical surface; both inner and outer walls share the axis 40 with the rotational axis of the piston hubs 30C and 32C (not shown in FIG. 5).

[0048] The outer cover 59, the piston hub 32C, and the chamber ring 47 form a groove 106 along the inner edge of the cylindrical crevice between the outer cover 59 and the piston hub 32C. The bridge seal 61 is housed in a bridge seal groove on the outer convex surface of the piston 32A between the piston rings 52, facing the inner end of the cylindrical crevice along the border between the outer cover 59 and the piston hub 32C. A spring means placed in the back of the bridge seal 61 pushes the bridge seal against the outer cover 59 and covers the groove 106.

[0049] Similarly, the outer cover 59, the piston hub 30C, and the chamber ring 48 form a groove 107 along the inner edge of the cylindrical crevice between the outer cover 59 and the piston hub 30C. The bridge seal 62 is housed in a bridge seal groove on the outer convex surface of the piston 32A between the piston rings 52, facing the inner end of the cylindrical crevice along the border between the outer cover 59 and the piston hub 30C. A spring means placed in the back of the bridge seal 62 pushes the bridge seal against the outer cover 59 and the piston hub 30C, and covers the groove 107.

[0050] Similarly, the outer cover 65, the piston hubs 30C and 32C and the chamber ring 46 form a groove 108 along the inner edge of the crevice between the piston hubs 30C and 32C. The bridge seal 65 is housed in a bridge seal groove on the outer convex surface of the piston 32A between the piston rings 52, facing the outer end of the crevice along the border between the piston hubs 30C and 32C. A spring means placed in the back of the bridge seal 65 pushes the bridge seal against the piston hub 30C, and covers the groove 108. The bridge seal 65 is equipped with a centrifugal force containment system (not shown in FIG. 5, but shown in FIG. 13).

[0051] The surface of the piston 32A comprises two half circular segments 32A-1 and 32A-3 and a rectangular segment 32A-2 between them. A circular shaped piston surface, which is the most desirable piston surface design, is a special case, in which the rectangular shaped segment is diminished to null. FIG. 6 of the drawings shows a side view of the piston 32A with the piston rings 52, and the bridge seals 62 and 65, taken from B-B of FIG. 5. Note that the cylindrical crevices between the outer cover 59 and the piston hubs 30C and 32C are located substantially at the extension of the border line between the upper half circular segment 32A-1 and the rectangular segment 32A-2 of the piston surface. Similarly, the crevice between the two piston hubs 30C and 32C is located substantially at the extension of the line that divides the piston surface in identical right and left halves (in the figure).

[0052] Reference is now made to FIGS. 7 and 8 of the drawings, which schematically illustrate a mechanism 170 that is used to contain the centrifugal force working on the outer part of the piston ring 52, wherein the outer part is the piston ring segment between a boss 113 and a stub end 109 of the piston ring 52. The mechanism 170 which is imbedded in the piston 32A includes enlarged piston ring stub end 109 with a pin 110 in a hole 110A at the end of the outer part of the piston ring 52; a lever/weight 112 with a noncircular hole 111A; and a pin 111 housed in a hole 111A, wherein the lever is articulately connected to the end of the outer part of the piston ring 52 at a pin 110 in a hole 110A. The lever/weight 112 is supported by the pin 111 that is affixed to the piston 32A and functions as a fulcrum for the mechanism housed in the noncircular hole 111A in the lever/weight 112. The size and weight of the lever/weight 112, and the location of the hole 111A are adjusted in such a manner that the centrifugal force generated by the lever/weight 112 will substantially equal the centrifugal force generated by the outer part of the piston ring 52. The noncircular hole 111 is longer in the direction parallel to the rotational axis 40 (horizontally in FIG. 7) so that the whole centrifugal force containment mechanism 170 may move in that direction as the piston ring stub end 109 moves, but the centrifugal force containment mechanism 170 will not move in the inner-outer direction (vertically in FIG. 7). The piston ring stub end 109 will be able to move in the inner-outer direction (vertically in FIG. 7) independently of centrifugal force effects by pivoting around the pin 111.

[0053] A similar centrifugal force containment mechanism 171 is employed for the inner part of the piston ring 52 which mechanism includes an enlarged piston ring stub end 115 with a pin 116 in a hole 116A, a lever/weight 118 with a hole 117A, and a pin 117 housed in the hole 117A and affixed to the piston 32A. The lever/weight 118 is articulately connected to the stub end 115 of the inner part of the piston ring 52 by the pin 116. The inner part of the piston ring 52 is the segment of the piston ring 52 between the boss 113 and the piston ring stub end 115. The lever/weight 118 may pivot around the pin 117 in the noncircular hole 117A, which functions as a fulcrum. The size and weight of the lever/weight 118 and the location of the hole 117A are adjusted in such a manner that the centrifugal force generated by the lever/weight 118 will be substantially the same as the centrifugal force generated by the inner part of the piston 52. The noncircular hole 117 is longer in the direction parallel to rotational the axis 40 (horizontally in FIG. 7) so that the whole centrifugal force containment mechanism may move in that direction as the piston ring stub end 115 moves, but it will not move in the inner-outer direction. The piston ring stub end 115 will be able to move in the inner-outer direction (vertically in FIG. 7) independently of the centrifugal force effects.

[0054] The centrifugal containment mechanisms 170 and 171 are housed in the crevices 119 and 120, respectively. The piston ring 52 is supported by the boss 113, which is located at the start of the curved outer segment of the piston ring 52. The piston ring 52 is pushed against the chamber wall at all times by either mechanical force such as a metal spring means placed in the inner clearance of the piston ring groove and/or by the force generated by the piston ring itself.

[0055]FIG. 8 of the drawings shows a side view of the centrifugal force containment mechanism 170 at the upper part of the piston ring 52 viewed from C-C in FIG. 7. The parts of the mechanism 170 shown in FIG. 8 include the pin 110 in the hole 110A, the pin 111 that functions as the fulcrum, the lever/weight 112, and the space 119 that houses the mechanism 170. The space 119 is provided within the outer shell of the piston 32A, and is securely covered by a plate 39.

[0056] Reference is now made to FIG. 9 of the drawings, wherein an enlarged view of the groove 107 along the inner part of the cylindrical crevice between the outer cover 59 and the piston hub 30C is shown. FIG. 9 shows the case wherein part of the working chamber wall 33A created by the outer cover 59 and part of the working chamber wall 33B created by the piston hub 30C are perfectly aligned. The cross-section of groove 107 is expected to be in the order of a tenth of a square millimeter (note that the figure is not in scale and it exaggerates the size of the groove 107).

[0057] Reference is now made to FIGS. 10 and 11 of the drawings, wherein an enlarged view of the groove 107 and its vicinity is shown. Here, the part of the working chamber wall created by the outer cover 59 (33A in the figure), and the part of the working chamber wall created by the piston hub 30C (33B in the figure) are not aligned. When the amount of misalignment becomes larger than a certain limit, both bridge seal and piston ring will have to be redesigned in such a manner that they can accommodate the condition. FIG. 10 shows a new version of a bridge seal in which the bridge seal 62 shown in FIG. 9 is sliced into two parts 62A and 62B, both housed in one groove, and in which 62A and 62B has its own spring support system at the back clearance in the groove. The bridge seal parts 62A and 62B together are able to completely cover the groove 107. FIG. 11 shows an enlarged view of the groove 107 and its vicinity and a new version of a piston ring in which the boss 113 of the piston ring 52 shown in FIG. 9 is cut into two parts 113A and 113B, and the piston ring 52 is cut into two parts, 52A and 52B. By doing so, the piston ring part 52A is able to completely seal off the space between the piston 32A and the working chamber wall part 33A, and the piston ring 52B is able to seal off the space between the piston 32A and the working chamber wall part 33B.

[0058] Reference is now made to FIG. 12 of the drawings, wherein an enlarged view of the groove 106 between the outer cover 59 and the piston hub 32C is shown. In this case, because the piston 32A and the piston hub 32C are integral parts of the piston assembly 32, misalignment of partial chamber walls cannot occur. To ensure that the piston ring 52 will completely seal off the space between the chamber wall 33 and the piston 32A, however, necessary horizontal movements (in the figure) of the piston ring 52 must be allowed. Making clearances 72A and 72B of the piston ring groove large enough for any necessary movements of the piston ring 52 serves the purpose. For the bridge seal 61 to be able to completely cover the groove 106, the cylindrical inner surface of the bridge seal groove 73B and the cylindrical surface 73A of the piston hub 32C along the crevice must be inline.

[0059] Reference is now made to FIG. 13 of the drawings, wherein an enlarged view of the groove 108 between the piston hubs 30C and 32C is shown. In this case again, nonalignment of the chamber wall cannot occur. To ensure that the piston ring 52 will completely seal off the space between the chamber wall 33 and the piston 32A, necessary vertical movements (in the figure) of the piston ring 52 must be allowed. Making clearances 74A and 74B of the piston ring groove large enough for any necessary movements of the piston ring 52 serves this purpose. In addition, for the bridge seal 65 to be able to completely cover the groove 108, the side surface 75B of the bridge groove and the surface 75A of the piston hub 32C along the crevice must be inline. A spring means 151, which presses the bridge seal 65 inward, is placed in the back (outer) clearance of the bridge seal groove. Adverse effect of centrifugal force on bridge seal 65 is contained by a centrifugal force containment mechanism 172, which includes a lever/weight 150 and a fulcrum 152. The centrifugal force on the lever/weight 150 and on the bridge seal 65 results in a balance such that the bridge seal remains in position and covers the groove 108.

[0060] Now reference is made to FIG. 14 of the drawings, wherein a cross-sectional view of chamber ring 46 in a groove in the piston hub 32C is shown. The chamber ring 46 is housed in a chamber ring groove 121. The chamber ring 46 has a broken segment 124 and in that segment, a spring means 125 is placed in such a manner that the spring means will push the chamber ring 46 outward toward the outer wall of the groove, and this pressure with the spring effects of the chamber ring 46 prevent air leaks along the crevice between the two piston assemblies. A metal pin 122 is inserted in a groove between chamber ring 46 and the piston hub 32C to force the chamber ring 46 to rotate at the same speed as the piston assembly 32 around the rotational axis 40, even though, as shown in FIG. 14, it is possible to insert a spring means in the inner clearance of the groove to push the chamber ring 46 outward.

[0061] Note that the pistons 30A, 30B, 32A, and 32B are all of substantially identical design, and therefore what is said about the piston 32A holds true for other pistons.

[0062] Alternative Seal Means Design

[0063] Reference is now made to FIG. 15 of the drawings, wherein a cross-sectional view of an alternative design piston 32A-A and chamber rings 46-A, 47-A, and 48-A are shown. In this alternative design version, the piston surface is substantially ellipsoidal in shape. A boss 113-A is provided at the start of the outer curved segment of a piston ring 52-A to prevent the piston ring from being pushed outward by centrifugal force. Crevices between outer cover 59-A and piston hubs 30C-A and 32C-A are located at the extension of the line that divides the ellipsoidal shaped piston surface into two substantially identical outer and inner halves. Similarly, a crevice between the piston hubs 30C-A and 32C-A is located at the extension of the line that divides the ellipsoidal shaped piston surface into two substantially identical left and right halves.

[0064] The chamber ring 46-A is housed in a groove in the piston hub 32C-A. Spring means 49 in the back clearance of the chamber ring groove pushes the chamber ring 46-A against the working surface of the piston hub 30C-A. The chamber ring 46-A is also pushed against the outer wall (upper wall in FIG. 15) of the chamber ring groove by a similar mechanism used for the chamber ring 46, shown in FIG. 14 and described above.

[0065] The chamber ring 47-A and 48-A are housed in grooves in the outer cover 59-A, and they are pressed against the working surface of the piston hubs 32C-A and 30C-A by spring means 51 and 53 in the back clearances of the chamber ring grooves, respectively. The spring means 51 is connected to the outer cover 59-A and the chamber ring 47-A so that the chamber ring 47-A can be positioned in its proper location; i.e., vertically, substantially at the center of the chamber ring groove. Similarly, the spring means 53 is connected to the outer cover 59-A and the chamber ring 48-A so that the chamber ring 48-A can be positioned in its proper location (vertically, substantially at the center of the chamber ring groove).

[0066] Reference is now made to FIG. 16 of the drawings, which schematically illustrates a mechanism 270 that is used to contain the centrifugal force working on both the outer and inner parts of a piston ring 52-B, wherein the outer part is the piston ring segment between a boss 113-B and a stub end 209 of the piston ring 52-B, and the inner part is the piston ring segment between the boss 113-B and a stub end 216 of the piston ring 52-B. The mechanism 270 which is imbedded in the piston 32A-B includes an enlarged piston ring stub end 209 with a pin 210 in a hole 210A at the end of the outer part of the piston ring 52-B; an enlarged piston ring stub 216 with a pin 212 in a hole 212A at the end of the inner part of the piston ring 52-B; a lever 215 with a noncircular hole 211A, which accommodate a pin 211, wherein the lever is articulately connected to the end of the outer part of the piston ring 52-B at the hole 210A with the pin 210, and to the end of the inner part of the piston ring at the hole 212A with the pin 212. A lever 215, which is supported by the pin 211, is affixed to the piston 32A-B and functions as a fulcrum for the centrifugal force containment mechanism 270. The lever 215 is housed in the noncircular hole 211A in the lever 215. The size and weight of the enlarged stub end 216 and the location of the hole 211A are adjusted in such a manner that the centrifugal force generated by the outer part of the piston ring 52B will substantially equal the centrifugal force generated by the inner part of the piston ring 52-B. Noncircular hole 211 is longer in the direction parallel to the rotational axis 40 (horizontally in FIG. 16) so that the whole centrifugal force containment mechanism 270 may move in that direction as either of the piston ring stub ends 209 or 216 move, but will not move in the inner-outer direction (vertically in FIG. 16). The piston ring stub ends 209 and 216 will be able to move in the inner-outer direction (vertically in FIG. 16) independently of the centrifugal force effects by pivoting around the pin 211. FIG. 16 depicts a circular piston surface, but this type of centrifugal force containment system may be adopted in a piston of any surface shape.

[0067] We expect that bridge seals will reduce the amount of gas leaked from the grooves. Those bridge seals, however, cause much friction especially at high rotational operating speeds of the engine. Thus, the decision of whether or not to implementing bridge seals must be made on the basis of their effectiveness on engine performance.

[0068] The effectiveness of bridge seals will diminish if a gap is formed between the bridge seal and a piston ring. Formation of a gap will be prevented by adopting such methods as cutting the bridge seal at the middle and inserting a spring means in between the two half pieces of the bridge seal, or providing a flange or boss at each end of the bridge seal fitted into a groove to accommodate the flange or boss.

[0069] Piston rings may be housed in grooves that are slightly wider (by about 0.2 mm) than the piston rings, as is usually done in a conventional reciprocating engine. Then, in the combustion phase, high-pressure air seeps into the back clearance of the piston grooves through the side clearance and pushes the piston rings against the chamber wall to keep the subchamber airtight.

[0070] Note that any combination of different piston designs, piston ring designs, and chamber ring designs is allowable.

[0071] Lubricant Oil Delivery/Recycling System

[0072] Reference is now made to FIG. 17 of the drawings, wherein a lubricant oil delivery/recycling system of a working chamber assembly is shown. Lubricant oil delivered by the oil delivery system originates at the oil pump (not shown) and reaches various parts of the working chamber assembly. The oil delivery system comprises bores, which are shown by thick real lines, and crevices between different moving parts shown by thick dotted lines in FIG. 17. Lubricant oil is delivered to all friction-causing surfaces of the working chamber assembly including piston rings, chamber rings, bridge seals, journal and side wall rings. Oil is pumped into the working chamber through a bore 130, which extends along the rotational axis 40 at the center of the inner piston shaft 38.

[0073] Lubricant oil carried by a bore 130 is diverted at five points along its route into radially extending bores 131, 132, 133, 134, and 135. Each of the bores 131 through 135 may have a different diameter to regulate the amount of oil diverted to it. From these diverge points on, centrifugal force will become the main means of powering oil delivery. The oil bore 131 delivers oil to the journal ring 103, and via a crevice 136 to the side wall ring 101; the oil bore 132 in the piston segment of the piston hub 32C (see FIG. 18) delivers oil to the chamber ring 47; the oil bore 133 delivers oil to the journal ring 100, and via a crevice 137, to the chamber ring 46, and then afterwards, via a crevice 138, to the piston ring 52; the oil bore 134, via the oil bore 139 in the piston segment of the piston hub 30C (see FIG. 19) delivers oil to the chamber ring 48; the and oil bore 135 delivers oil, via the oil bore 140, to the journal ring 104 and via a crevice 141 to the side wall ring 102. Excess oil in the crevice between the inner shaft 38 and the outer shaft 36 will lubricate the journal ring 105. After lubricating these friction-causing parts, used oil will reach the lower part of the grooves that house the chamber rings 47 and 48, and the oil drainage gutter 143. Oil bores/pipes 142 connected to the chamber ring grooves and a pipe 144 connected to the oil drainage gutter carry the used oil to oil filter means and then back to the oil pump (not shown).

[0074] Reference is now made to FIG. 18 of the drawings, wherein a cross-sectional view of the chamber ring 47 and the piston hub 32C, which rotate around the rotational axis 40 in the direction indicated by the arrow 42, is shown. In FIG. 18, the oil bore 130 extends along the rotational axis 40. The oil bore 132 within the piston segment (32A and 32B) of the piston hub 32C, extends outward radially from the bore 130 to the cylindrical crevice where the piston hub 32C and the chamber ring 47 rotatably contact each other. A shallow depression 145 is provided at the end of the oil bore 132, and the oil in depression 145 coats the inner wall of the chamber ring 47. Lubrication of the journal ring 103 is done essentially in the same manner shown in FIG. 18 and described above. By changing the reference numeral 32C to 38 to identify inner piston shaft 38; the reference numeral 47 to 103 to identify journal ring 103; and the reference numeral 132 to 131 to identify the oil bore 131 in FIG. 18 (also see FIG. 17), FIG. 18 will be transformed to show the oil delivery system to the journal ring 103.

[0075] Reference is now made to FIG. 19 of the drawings, wherein a cross-sectional view of the chamber ring 48, the inner coaxial shaft 38, and the piston hub 30C is shown. Both the inner piston shaft 38 and the piston hub 30C rotate around the rotational axis 40 in the direction indicated by the arrow 42. The oil bore 130 extends along the rotational axis 40 at the center of the inner piston shaft 38. The oil bore 134 branches out radially from the bore 130. The oil carried by the oil bore 134 is sprayed around the inner surface of the piston hub 30C, but it is funneled into a shallow depression 147 through an opening 146 and the oil bore 139, which are within the piston segment (30A and 30B) of the piston hub 30C. Oil in a shallow depression 147 coats the inner surface of the chamber ring 48. By changing reference numeral 48 to 104 to identify journal ring 104; the reference numeral 30C to 36 to identify outer piston shaft 36; the reference numeral 134 to 135 to identify oil bore 135; and the reference numeral 139 to 140 to identify oil bore 140 in FIG. 19 (also see FIG. 17), FIG. 19 will be transformed to show the oil delivery system to journal ring 104.

[0076] Reference is now made to FIG. 20 of the drawings, wherein an enlarged view of the oil route between the oil delivery bore 130 and the piston 32A is shown. As shown in the figure, the oil bore 133 branches out from the oil bore 130 at the extension of crevice 137 between the piston hubs 30C and 32C. The oil bore 133 delivers oil to the inner surface of the journal ring 100. From that point on, various routes are possible for oil to reach the gap 138 between the outer convex surface of the piston 32A and the working chamber wall 33. The main oil route to the gap 138 will follow the path made by a bore in the middle of the journal ring 100, the crevice 137 between the piston hubs 30C and 32C, and a special oil bore 155 that connects the side clearance of the chamber ring 46 in the piston hub 32C and the crevice 138 between the piston 32A and the chamber wall 33. Oil delivered to the inner most part of the crevice 138 spreads out (or up in FIG. 20) by centrifugal force. Rotating the piston ring 52 coats the right half of the working chamber wall. A similar oil bore (to bore 155) is provided in the piston hub 30C and the piston 30A. The piston ring 50 coats the left half of the working chamber wall with a thin coat of oil through associated bores and crevices (not shown in the figure). Both journal ring 100 and the chamber ring 46 have oil grooves (not shown) on the their outer surface (upper surface in FIG. 20) to coat their working surfaces with oil.

[0077] Reference is now made to FIG. 21 of the drawings, wherein an enlarged view of the bridge seal 62 is shown. The bridge seal 62 seals off the crevice 138 between the working chamber wall 33 and the piston 32A's outer convex surface. A tunnel 156 that connects the two sides of the crevice is bored, and extends from the outer convex surface of the piston 32A through the bridge seal 62 and back to the outer convex surface of the piston 32A. A similar bore to tunnel 156 is provided in the bridge seal 65 as part of the bore 155 also.

[0078] The invention having been described in detail in accordance with the requirements of the U.S. Patent Statutes, various other changes and modification will suggest themselves to those skilled in this art. A four-piston engine, which has two pistons per piston assembly, is used as an example in this application because of its simplicity, but the number of pistons per piston assembly is not limited to two: any number that is a multiple of two is acceptable. The sealing system and oil delivery/recycling system described in this invention may be used in both diesel and spark plug ignition engines. It is intended that the above and other such changes and modifications shall fall within the spirit and scope of the invention defined in the appended claims. 

I claim:
 1. Working chamber assembly of a rotary piston engine comprising, outer cover and first and second piston assemblies forming a working chamber, each of said piston assemblies including a piston hub, at least one pair of diametrically opposed pistons, rotatable about a rotational axis of said pistons dividing said working chamber into a plurality of pairs of diametrically opposed subchambers, said piston hub of said first piston assembly and said piston hub of second piston assembly being separated by a crevice between them, a seal means including first and second facing grooves having outer walls in said respective first and second piston hubs, and a chamber ring located in said facing first and second grooves and extending therebetween, said chamber ring being pressed against said outer wall of said facing grooves by spring effect of said chamber ring for sealing off leaks from said working chamber through said crevice.
 2. Working chamber assembly of a rotary piston engine as defined in claim 1 including mechanical means for pressing said chamber ring against said outer walls of said facing grooves.
 3. Working chamber assembly of a rotary piston engine comprising, outer cover and first and second piston assemblies forming a working chamber, each of said piston assemblies including a piston hub, at least one pair of diametrically opposed pistons, rotatable about a rotational axis of said pistons dividing said working chamber into a plurality of pairs of diametrically opposed subchambers, said piston hub of first piston assembly and said outer cover being separated by a crevice between them, said piston hub of second piston assembly and said outer cover being separated by a crevice between them, at least one bridge seal groove in said outer convex surface of each of said pistons extending between said two piston ring grooves, bridge seals housed in said bridge seal grooves, spring means housed in said bridge seal groove for pressing said bridge seals against said piston hub and outer cover at said crevices.
 4. Working chamber assembly of a rotary piston engine as defined in claim 3, wherein said bridge seal comprises first and second sections and first and second spring means housed in said bridge seal groove, said first spring means pressing said first bridge seal against said outer cover at said crevices, said second spring means pressing said second bridge seal against said piston hubs at said crevices.
 5. Working chamber assembly of a rotary piston engine comprising, outer cover and first and second piston assemblies forming a working chamber, each of said piston assemblies including, a piston hub, at least one pair of diametrically opposed pistons, rotatable about a rotational axis of said pistons dividing said working chamber into a plurality of pairs of diametrically opposed subchambers, wherein said piston hub of first piston assembly and said outer cover being separated by a crevice between them, said piston hub of second piston assembly and said outer cover being separated by a crevice between them, each of said pistons having piston surfaces comprising outer and inner half circular segments and a rectangular segment in between them, and said crevices between said outer cover and piston hubs being located along the extension of the border between said outer half circular portion and rectangular portion of said piston surface.
 6. Working chamber assembly of a rotary piston engine comprising, outer cover and first and second piston assemblies forming a working chamber, each of said piston assemblies including, a piston hub, at least one pair of diametrically opposed pistons, rotatable about a rotational axis of said pistons dividing said working chamber into a plurality of pairs of diametrically opposed subchambers, wherein said piston hub of said first piston assembly and said outer cover being separated by a crevice between them, said piston hub of said second piston assembly and said outer cover being separated by a crevice between them, each of said pistons having a substantially ellipsoidal shaped piston surfaces, said ellipsoidal shaped piston surface of each of said pistons comprising substantially identically shaped outer and inner half segments, and said crevices between said outer cover and piston hubs being located along the extension of the border between said outer half and inner half of said piston surface.
 7. Working chamber assembly of a rotary piston engine comprising, outer cover and first and second piston assemblies forming a working chamber, each of said piston assemblies including, a piston hub, at least one pair of diametrically opposed pistons, rotatable about a rotational axis of said pistons dividing said working chamber into a plurality of pairs of diametrically opposed subchambers, each of said pistons having an outer convex surface, piston ring grooves in said outer convex surface, and piston rings in said piston ring grooves, each of said first and second pistons including first and second means to contain centrifugal force on said piston ring, wherein said piston ring having a boss at a mid section which boss divides said piston ring into outer and inner parts, one end of said outer part of piston ring being articulately connected to said first means to contain centrifugal force, one end of said inner part of piston ring being articulately connected to said second means to contain centrifugal force, each of said first and second means to contain centrifugal force including a fulcrum and a lever/weight for substantially balancing centrifugal force generated by each half of said piston ring and associated lever/weight.
 8. Working chamber assembly of a rotary piston engine as defined in claim 7, wherein said piston ring comprises first and second sections separated at the middle of said boss.
 9. Working chamber assembly of a rotary piston engine comprising, outer cover and first and second piston assemblies forming a working chamber, each of said piston assemblies including, a piston hub, at least one pair of diametrically opposed pistons, rotatable about a rotational axis of said pistons dividing said working chamber into a plurality of pairs of diametrically opposed subchambers, each of said pistons having an outer convex surface, piston ring grooves in said outer convex surface, and piston rings in said piston ring grooves, each of said first and second pistons including a means to contain centrifugal force on said piston ring, wherein said piston ring having a boss at a mid section which boss divides said piston ring into outer and inner parts, one end of said outer part of piston ring being articulately connected to said means to contain centrifugal force, one end of said inner part of piston ring being articulately connected to said means to contain centrifugal force, said means to contain centrifugal force including a fulcrum and a lever for substantially balancing centrifugal force generated by each half of said piston ring.
 10. Working chamber assembly of a rotary piston engine as defined in claim 9, wherein said piston ring comprises first and second sections separated at the middle of said boss.
 11. Working chamber assembly of a rotary piston engine comprising, outer cover and first and second piston assemblies forming a working chamber, each of said piston assemblies including, a piston hub, at least one pair of diametrically opposed pistons, rotatable about a rotational axis of said pistons dividing said working chamber into a plurality of pairs of diametrically opposed subchambers, said piston hubs of said first and second piston assemblies being separated by a crevice between them, a seal means including a groove having a back clearance in said first piston hub, and a chamber ring in said groove, and a spring means in said back clearance of said groove; said chamber ring being pressed against said second piston hub by a spring means for sealing off leaks from said working chamber through said crevice.
 12. Working chamber assembly of a rotary piston engine as defined in claim 11 including mechanical means for pressing said chamber ring against said outer walls of said facing grooves.
 13. Working chamber assembly of a rotary piston engine comprising outer cover, and first and second piston assemblies forming a working chamber, said outer cover including an exhaust port, said first piston assembly including at least one pair of diametrically opposed pistons and attached inner coaxial shaft, said second piston assembly including at least one pair of diametrically opposed pistons and attached outer coaxial shaft, said piston assemblies being rotatable about a rotational axis of said pistons and dividing said working chamber into a plurality of pairs of diametrically opposed subchambers, lubricant oil delivery mechanism including oil delivery bores for delivering lubricant oil to working chamber assembly.
 14. Working chamber assembly as defined in claim 13, wherein said oil delivery bores include an axial bore in said inner piston shaft.
 15. Working chamber assembly as defined in claim 13, wherein said lubricant oil delivery means uses centrifugal force as a means to power oil delivery.
 16. Working chamber assembly as defined in claim 13 including an oil drainage gutter attached to an edge of said exhaust port at said outer cover. 